This invention relates to compositions, dyes, cartridges, ink jet printers and to their use in ink jet printing.
Ink jet printing methods involve a non-impact printing technique for printing an image onto a substrate using ink droplets ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate.
There are many demanding performance requirements for dyes and inks used in ink jet printer. For example they should desirably exhibit some or all of the following properties. They should provide sharp, non-feathered images having good water-fastness, light fastness and/or optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzle. The most popular ink jet printers are the thermal and piezoelectric ink jet printers.
We have now found that very good ink jet printing inks may be prepared having the compositions defined below using a specific class of dyes that give stable dye resin inks with some or all of these advantageous properties.
According to the present invention there is provided a composition comprising water, a water-dissipatable polymer and one or more dyes of Formula (1): 
wherein:
R1 and D are each independently H or a substituent;
R2 and R3 are each independently optionally substituted alkyl, aryl or aralkyl, or R2 and R3 together with the carbon atom to which they are attached form an optionally substituted ring;
R4 and R5 are each independently H or optionally substituted alkyl, aryl or aralkyl; and
R6 is optionally substituted alkyl, aryl or aralkyl.
When R1 or D is a substituent it is preferably halo; optionally substituted alkyl, aryl or aralkyl; or a group of formula xe2x80x94Xxe2x80x94R7 wherein X is O, S, SO, SO2 or NR8 wherein R7 and R8 are each independently H or optionally substituted alkyl, aryl or aralkyl.
When R1, R2, R3, R4, R5, R6, R7 or R8 is optionally substituted alkyl it is preferably optionally substituted C1-6-alkyl.
When R1, R2, R3, R4, R5, R6, R7 or R8 is optionally substituted aryl it is preferably optionally substituted C6-12-aryl, more preferably optionally substituted phenyl or naphthyl.
When R1, R2, R3, R4, R5, R6, R7 or R8 is optionally substituted aralkyl it is preferably optionally substituted benzyl or xylyl.
R1 and D are preferably each independently H, optionally substituted C1-6-alkyl, or a group of formula xe2x80x94Xxe2x80x94R7 wherein X is O, S, SO, SO2 or NR8 wherein R7 and R8 are each independently H or optionally substituted C1-6-alkyl.
X is preferably O, S or NR8 wherein R8 is H or C1-6-alkyl.
R2 and R3 are preferably each independently optionally substituted C1-6-alkyl, or R2 and R3 together with the carbon atom to which they are attached form an optionally substituted 5- or 6-membered ring, especially an optionally substituted cyclopentane or cyclohexane ring.
R4 and R5 are preferably each independently H or optionally substituted C1-6-alkyl, more preferably H or C1-6-alkyl.
R6 is preferably optionally substituted C1-6-alkyl, more preferably C1-6-alkyl.
R7 is preferably optionally substituted C1-6-alkyl, more preferably optionally substituted C1-4-alkyl.
R8 is preferably H or C1-6-alkyl.
The optional substituents which may be present on R1 to R8 or on D are preferably each independently selected from carboxy, sulpho, nitro, halo (especially bromo, chloro and fluoro), alkyl (especially C1-4-alkyl), alkoxy (especially C1-4-alkoxy), hydroxy, amine (especially xe2x80x94NHR9), mercapto, thioalkyl (especially C1-4-thioalkyl), cyano, ester (especially xe2x80x94OCOR9 or xe2x80x94COOR9) and amide (especially xe2x80x94CONHR9), wherein R9 is H or optionally substituted C1-4-alkyl (preferably H or C1-4-alkyl).
In one embodiment of the present invention R2 and R3 are free from the following substituents: xe2x80x94NO2, xe2x80x94CN, xe2x80x94Cl, xe2x80x94Br, xe2x80x94F, xe2x80x94OH, xe2x80x94OC1-4-alkyl, xe2x80x94CONH(C1-4-alkyl), xe2x80x94CONH2, xe2x80x94COOC1-4xe2x80x94(CH2)1-4xe2x80x94CN, xe2x80x94OCO(C1-4-alkyl) and xe2x80x94COO(C1-4-alkyl).
In a second embodiment of the present invention at least one of R2 and R3 carries a substituent selected from xe2x80x94NO2, xe2x80x94CN, xe2x80x94Cl, xe2x80x94Br, xe2x80x94F, xe2x80x94OH, xe2x80x94OC1-4-alkyl, xe2x80x94COOC1-4xe2x80x94(CH2)1-4xe2x80x94CN, xe2x80x94CONH2, xe2x80x94CONH(C1-4-alkyl), xe2x80x94OCO(C1-4-alkyl) and xe2x80x94COO(C1-4-alkyl).
The preferred optional substituents for R8 are said optional substituents are each independently selected from carboxy, sulpho, nitro, halo, alkyl, alkoxy, hydroxy, amine, mercapto, thioalkyl, cyano, ester and amide, more preferably from xe2x80x94NO2, xe2x80x94CN, xe2x80x94Cl, xe2x80x94Br, xe2x80x94F, xe2x80x94OH, xe2x80x94OC1-4-alkyl, xe2x80x94OC1-4-alkylenexe2x80x94CN, xe2x80x94CONH2, xe2x80x94COOC1-4xe2x80x94(CH2)1-4xe2x80x94CN, xe2x80x94OCO(C1-4-alkyl) and xe2x80x94COO(C1-4-alkyl), especially from xe2x80x94CN and xe2x80x94COO(C1-4-alkyl), especially xe2x80x94CN. Preferably R8 carries one or two substituents, more preferably one substituent.
Any alkyl groups in dyes of Formula (1) may be branched or straight chain. Preferred branched chain alkyl groups are xcex1-branched alkyl groups.
The dyes may be in any form, for example in the form of a salt. Formula (1) includes all tautomers, stereoisomers, zwitterions, polymorphs, and isotopes of dyes falling within the formula.
Salts of Formula (1) may be formed from one or more organic and/or inorganic bases or acids. Preferred salts of Formula (1) are insoluble in water.
The compositions preferably contain from 1 to 10, more preferably from 1 to 6, especially from 1 to 3, more especially 1 dye of Formula (1).
The dye of Formula (1) is preferably insoluble in water and soluble in the water-dissipatable polymer. Therefore the dye is preferably free from carboxy and sulpho groups, for example it is preferably a disperse or solvent-soluble dye. Disperse and solvent soluble dyes are distinct from pigments in that pigments are insoluble in organic solvents and polyesters whereas disperse and solvent soluble dyes are soluble in organic solvents and polymers.
According to a second feature of the present invention there is provided a dye of Formula (1) as hereinbefore defined. The preferences for the dye of Formula (1) are as hereinbefore described in relation to the preferred dyes used in the inks of the invention.
The dyes of Formula (1) may be prepared by diazotising a suitable amine, using a diazotising agent, preferably below 5xc2x0 C., and coupling to a suitable coupling component. A preferred diazotising agent is sodium nitrite. A suitable amine is of Formula (2) and a suitable coupling component is of Formula (3): 
wherein R1, R2, R3, R4, R5, R6 and D are as hereinbefore defined.
Generally from 3 to 5 molar equivalents of the amine are used relative to the amount of the coupling component. If desired the resultant dye may be further reacted, for example by condensation with an acyl halide or an anhydride to convert some or all of any hydroxy groups to ester groups.
The composition may contain further dyes other than those of Formula (1), although this is not normally necessary.
The water-dissipatable polymer preferably bears ionised carboxy and/or sulphonate groups, especially ionised sulphonate groups, because these assist water dissipatability of the polymer. Such groups can be chain pendant and/or terminal.
The water-dissipatable polymer is preferably a water-dissipatable polyester. The water-dissipatable polyester can be prepared using conventional polymerisation procedures known to be effective for polyester synthesis. Thus, it is well known that polyesters contain carbonyloxy (i.e. xe2x80x94C(xe2x95x90O)xe2x80x94Oxe2x80x94) linking groups and may be prepared by a condensation polymerisation process in which an acid component (including ester-forming derivatives thereof) is reacted with a hydroxyl component. The acid component may be selected from one or more polybasic carboxylic acids, e.g. di- and tri-carboxylic acids or ester-forming derivatives thereof, for example acid halides, anhydrides or esters. The hydroxyl component may be one or more polyhydric alcohols or phenols (polyols), for example, diols, triols, etc. (It is to be understood, however, that the polyester may contain, if desired, a proportion of carbonylamino linking groups xe2x80x94C(xe2x95x90O)xe2x80x94NHxe2x80x94 (i.e. amide linking groups) by including an appropriate amino functional reactant as part of the xe2x80x9chydroxyl componentxe2x80x9d; such as amide linkages). The reaction to form a polyester may be conducted in one or more stages. It is also possible to introduce in-chain unsaturation into the polyester by, for example, employing as part of the acid component an olefinically unsaturated dicarboxylic acid or anhydride.
Polyesters bearing ionised sulphonate groups may be prepared by using the method, and using the materials, described in International Patent Publication number WO 98/14525 of Zeneca Limited, page 11, line 15, to page 13, line 7, which is incorporated directly herein by reference thereto.
Polyesters bearing ionised carboxy groups can be prepared by various means, for example by the method, and using the materials, described in International Patent Publication number WO 98/14525 of Zeneca Limited, page 13, line 9 to page 13, line 30, which is incorporated directly herein by reference thereto.
The water-dissipatable polyester may optionally have hydrophilic non-ionic segments, for example within the polyester backbone (i.e. in-chain incorporation) or as chain-pendant or terminal groups. Such groups may act to contribute to the dispersion stability or even water-solubility of the polyester. For example, polyethylene oxide chains may be introduced into the polyester during its synthesis by using as part of the hydroxyl component, ethylene oxide-containing mono, di or higher functional hydroxy compounds, especially polyethlene glycols and alkyl ethers of polyethylene glycols, examples of which include: 
wherein R8 is C1-20-alkyl, preferably C1-4-alkyl, more preferably methyl; n is 1 to 500; and p is 1 to 100.
A small segment of a polyethylene oxide chain could be replaced by a propylene oxide or butylene oxide chain in such non-ionic groups, but should still contain ethylene oxide as a major part of the chain.
The amount of ionised sulphonate and/or carboxy groups present in the polyester should be sufficient to provide or contribute to water-dissipatability of the polyester, although it should not be so high as to render the resulting polyester unacceptably water-sensitive. This amount will depend, inter alia, on factors such as the hydrophilicity/hydrophobicity of units provided by other monomers in the polyester synthesis or any surfactants (if used), and also the relative proportions of ionised sulphonate/carboxy groups. With regard to the last mentioned point, ionised sulphonate groups are more effective at providing or contributing to water-dissipatability than ionised carboxy groups and so can be used at considerably lower levels in comparison to ionised carboxy groups.
If the polyester is wholly or predominantly sulphonate stabilised (by which is meant the water dissipatability-providing groups are provided wholly or predominately by ionised sulphonate groups). The ionised sulphonate group content is preferably as described in International Patent Publication number WO 98/14255 of Zeneca Limited, page 14, line 31 to page 15, line 3, which is incorporated directly herein by reference thereto.
If the polyester is predominantly stabilised by ionised carboxy groups, the carboxylic acid value AV of the polyester is preferably within the range of from 20 to 140 mgKOH/g (more preferably 30 to 100 mgKOH/g).
Usually, the polyester is either predominantly sulphonate-stabilised or predominantly carboxylate stabilised (preferably the former).
If the polyester contains polyethylene oxide chains, the polyethylene oxide chain content should preferably not exceed 25% by weight (and more preferably should not exceed 15% by weight), based on the total weight of the polyester, in order to avoid unacceptable water-sensitivity. Therefore the amount is preferably 0 to 25% by weight (more preferably 0 to 15% by weight) based on the total weight of polyester.
The water-dissipatable polyester preferably has a number average molecular weight Mn of up to 30,000. The Mn is preferably in the range from 500 to 30,000, more preferably 1,000 to 25,000. These Mn lead to particularly good storage stability for the resultant inks. The measurement of Mn is well known to those skilled in the art, and may for example be effected using gel permeation chromatography in conjunction with a standard polymer such as polystyrene or polymethylmethacrylate of known molecular weight.
The water-dissipatable polyester preferably has a hydroxyl number of from 0 to 225 mg KOH/g, more preferably 0 to 125 mg KOH/g, especially from 0 to 50 mgKOH/g.
The ink preferably has a pH of 5 to 9, more preferably 5.5 to 8, especially 6 to 7.5. These preferences are based on increased ink stability.
The Tg of the water-dissipatable polyester (i.e. the temperature at which the polymer changes from a glassy, brittle state to a plastic, rubbery state) is preferably in the range xe2x88x9238xc2x0 C. to 105xc2x0 C., more preferably xe2x88x9220 to 70xc2x0 C., especially xe2x88x9210xc2x0 C. to 60xc2x0 C.
The esterification polymerisation processes for making the polyesters for use in invention composition are known and need not be described here in more detail. Suffice to say that they are normally carried out in the melt using catalysts, for example a tin-based catalyst, and with the provision for removing any water or alcohol formed from the condensation reaction.
The water-dissipatable polyester may be dissipated in water by adding the solidified melt directly into water. The solidified melt is preferably in a form such as flake (which can often be obtained directly from the melt) or comminuted solid (obtained for example by grinding). Alternatively, water can be added directly to the hot polyester melt until the desired solids content/viscosity is reached. Still further, the polyester may be dissipated in water by adding an aqueous pre-dissipation (or organic solvent solution) of the polyester to the water phase.
The water-dissipatable polyesters normally do not need an external surfactant when being dissipated into water, although such surfactants may be used to assist the dissipation if desired and in some cases can be useful in this respect because additional surfactants reduce the required amount of dissipating groups (i.e. sulphonate, and (mono alkoxy)polyalkylene chains if used).
The water-dissipatable polymer may also be formed by the method, and using the materials, described in International Patent Publication number WO 98/14525 of Zeneca Limited, page 16, line 8 to page 16, line 34, which is incorporated directly herein by reference thereto.
The dyed water-dissipatable polymer may be prepared by heating a water-dissipatable polymer and dye(s) at an elevated temperature, for example at a temperature in the range 35 to 150xc2x0 C., preferably from 40 to 90xc2x0 C. Simply mixing the dye and polymer in water at room temperature leads to a slight up-take of colour but heating is usually necessary for a full dyeing.
Preferably compositions according to the invention are prepared by mixing together (i) a solution of a dye(s) in a water-immiscible solvent and (ii) a mixture of a water-dissipatable polymer, water-miscible solvent and optionally water. Equally the compositions may be prepared by mixing together (i) a solution of a dye(s) in a mixture of a water-miscible solvent and a water-immiscible solvent and (ii) a water-dissipatable polymer and optionally water. In either case, if there is no water in component (ii) the water may be added to the mixture of (i) a (ii) subsequently to give acomposition according to the invention. However it is preferred for component (ii) to contain water. These processes lead to particularly good up-take of dye(s) by the polymer to give intensely coloured composition.
The amount of dye and water-dissipatable polymer contained in the composition will vary according to the depth of shade required. Typically, however, the composition will comprise
(a) from 0.5 to 15 parts, more preferably 0.8 to 10 parts, especially 1 to 5 parts in total of the dye(s);
(b) from 0.2 to 25 parts, more preferably 2 to 15 parts of a water-dissipatable polymer;
(c) from 40 to 90 parts, more preferably from 50 to 80 parts of water; and
(d) from 0 to 60 parts, more preferably 0 to 40 parts of organic solvent;
wherein all parts are by weight and the total number of parts of (a)+(b)+(c)+(d) add up to 100.
The number of parts of the water-dissipatable polymer is calculated on a 100% solids basis. For example 50 g of a 20% solids polymer is taken as 10 g of polymer.
The composition may also contain an organic solvent (as mentioned in (d) above) and this may be a mixture of organic solvents. In a preferred embodiment the composition contains an organic solvent comprising a water-miscible organic solvent and a water-immiscible organic solvent.
Suitable water-immiscible organic solvents include aromatic hydrocarbons, e.g. toluene, xylene, naphthalene, tetrahydronaphthalene and methyl naphthalene; chlorinated aromatic hydrocarbons, e.g. chlorobenzene, fluorobenzene, chloronaphthalene and bromonaphthalene; esters, e.g. butyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, benzyl benzoate, butyl benzoate, phenylethyl acetate, butyl lactate, benzyl lactate, diethyleneglycol dipropionate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di (2-ethylhexyl) phthalate; alcohols having six or more carbon atoms, e.g. hexanol, octanol, benzyl alcohol, phenyl ethanol, phenoxy ethanol, phenoxy propanol and phenoxy butanol; ethers having at least 5 carbon atoms, preferably C5-14 ethers, e.g. anisole and phenetole; nitrocellulose, cellulose ether, cellulose acetate; low odour petroleum distillates; turpentine; white spirits; naphtha; isopropylbiphenyl; terpene; vegetable oil; mineral oil; essential oil; and natural oil; and mixtures of any two or more thereof. Benzyl alcohol is especially preferred.
Suitable water-miscible organic solvents include C1-5-alkanols, e.g. methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol and isobutanol; amides, e.g. dimethylformamide and dimethylacetamide; ketones and ketone alcohols, e.g. acetone and diacetone alcohol; C2-4-ether, e.g. tetrahydrofuran and dioxane; alkylene glycols or thioglycols containing a C2-C6 alkylene group, e.g. ethylene glycol, propylene glycol, butylene glycol, pentylene glycol and hexylene glycol; poly(alkylene-glycol)s and thioglycol)s, e.g. diethylene glycol, thiodiglycol, polyethylene glycol and polypropylene glycol; polyols, e.g. glycerol and 1,2,6-hexanetriol; and lower alkyl glycol and polyglycol ethers, e.g. 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy) ethanol, 2-(2-butoxyethoxy)ethanol, 3-butoxypropan-1-ol, 2-[2-(2-methoxyethoxy)-ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)ethoxy]-ethanol; cyclic esters and cyclic amides, e.g. optionally substituted pyrollidones; sulpholane; and mixtures containing two or more of the aforementioned water-miscible organic solvents. Preferred water-miscible organic solvents are C1-6-alkyl mono ethers of C2-6-alkylene glycols and C1-6-alkyl mono ethers of poly(C2-6-alkylene glycols).
Component (d) of the above mentioned composition preferably comprises;
(i) 5 to 50% of a water-immiscible alcohol having at least six carbon atoms, (especially benzyl alcohol); and
(ii) 50 to 95% of a water-miscible solvent comprising;
(a) a cyclic ester or cyclic amide (especially an optionally substituted pyrrolidone);
(b) a water-miscible C1-6-alkyl mono ether of a C2-6-alkylene glycol or C1-6-alkyl mono ether of poly(C2-6-alkylene glycol); or
(c) a mixture of (a) and (b).
wherein all % are by weight and add up to 100%.
The water-immiscible solvent preferably has a solubility in water at 20xc2x0 C. of up to 50 g/l. The water-miscible solvent preferably has a solubility in water at 20xc2x0 C. of more than 50 g/l.
The preferred optionally substituted pyrrolidones, are 2-pyrrolidone, dimethyl pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and N-(2-hydroxyethyl)-2-pyrrolidone and mixtures thereof.
The ratio of water-miscible organic solvent to water-immiscible organic solvent is preferably 19:1 to 1:1, more preferably 8:1 to 1:1, especially 5:1 to 1:1.
Use of dyes has advantages over the use of pigments in that less dye is usually required than would be the case for a pigment, expensive milling is avoided, the composition are less likely to form a precipitate on standing, a far greater variety of shades are available and the resultant prints have good transparency. The composition of the present invention also benefit from good light- and water-fastness.
A valuable feature of the invention is the low tendency for blocking the nozzles of thermal ink jet printers. Many other water dispersible polymer composition work poorly or even not at all in thermal printers. Composition of the invention form discrete droplets on the substrate with little tendency for diffusing. Consequently sharp images can be obtained, resulting in excellent print quality and little if any bleed between colours printed side-by side.
Preferably the composition is an ink, more preferably an ink jet printing ink. When the composition is not an ink it may be used as concentrated colorant for the preparation of an ink.
Preferably the composition has been filtered through a filter having a mean pore size below 10 xcexcm, more preferably below 5 xcexcm especially below 2 xcexcm, more especially below 1 xcexcm. In this way reliability of the ink jet printer is improved by removing particulate matter which could otherwise block the fine nozzles of the printer.
A third feature of the invention provides a composition comprising a water dissipatable polymer and a dye as hereinbefore defined, preferably of Formula (1). In these compositions the preferred water-dissipatable polymers and dyes are as hereinbefore described. Such compositions may be dissipated in water and optionally mixed with further ingredients to give an ink, for example with one or more organic solvents.
The composition of the third feature of the present invention preferably comprises (a) 0.125 to 40 parts of a dye as hereinbefore defined (preferably of Formula (1) or (2)); and (b) 99.875 to 60 parts of a water-dissipatable polymer, wherein the total number of parts of (a) and (b) adds up to 100.
According to a further feature the present invention provides a process for printing an image on a substrate comprising applying thereto a composition comprising water, a water-dissipatable polymer and a dye as hereinbefore defined (preferably of Formula (1) or (2)) by means of an ink jet printer.
The ink jet printer emits droplets of the composition onto a substrate from a nozzle without bringing the nozzle into contact with the substrate. Preferably the ink jet printer is a thermal or piezoelectric ink jet printer.
The substrate is preferably a paper, an overhead projector slide or a textile material. Preferred textile materials are cotton, polyester and blends thereof.
When the substrate is a textile material the process for printing an image thereon according to the invention preferably further comprises the step of heating the resultant printed textile, preferably to a temperature of 50xc2x0 C. to 250xc2x0 C.
A further feature of the present invention is a cartridge suitable for use in an ink jet printer containing acomposition according to the invention. Also there is provided an ink jet printer containing acomposition according to the invention.
The invention is further illustrated by the following examples in which all parts and percentages are by weight unless specified otherwise.
Water-Dissipatable Polymer (xe2x80x9cResin 1xe2x80x9d)
To a glass reactor fitted with distillation column and condenser were charged ingredients A, B, D, F, G and 50% of C and 50% of H. The contents were heated with stirring to a reaction temperature of 210xc2x0 C. until the mixture was clear and the acid value was  less than 10 mg(KOH)gxe2x88x921. At this point E and the remainder of C and H were charged and the temperature raised to 230xc2x0 C. The reaction was continued under reduced pressure until an acid value of 5.3 mg(KOH)gxe2x88x921 was obtained. The resin was further characterised by a hydroxyl value=27.6 mg(KOH)gxe2x88x921, ICI Cone and Plate viscosity @125xc2x0 C.=80 poises and a Tg (onset)=25.4xc2x0 C. and a number average molecular weight by end group analysis of approximately 2000. The resin was readily dispersed in warm distilled water to give a clear solution having a solids content of 20% w/w (hereinafter xe2x80x9cResin 1xe2x80x9d).
Water-Dissipatable Polymer (xe2x80x9cResin 2xe2x80x9d)
To a glass reactor fitted with distillation column and condenser were charged ingredients A, B, C, E, G, H and 50% of D and 50% of I. The contents were heated with stirring to a reaction temperature of 210xc2x0 C. until the mixture was clear and the acid value was 1.25 mg(KOH)gxe2x88x921. At this point F and the remainder of D and I were charged and the temperature raised to 230xc2x0 C. The reaction was continued under reduced pressure until an acid value of 2.8 mg(KOH)gxe2x88x921 was obtained. The resin was further characterised by a hydroxyl value=19.7 mg(KOH)gxe2x88x921, ICI Cone and Plate viscosity @125xc2x0 C.=90 poises and a Tg (onset)=4xc2x0 C. The resin was readily dispersed in warm distilled water to give a clear solution having a solids content of 20% w/w. (hereinafter xe2x80x9cResin 2xe2x80x9d).
Water-Dissipatable Polymer (xe2x80x9cResin 3xe2x80x9d)
To a glass reactor fitted with distillation column and condenser were charged ingredients A, B, D, E, F, G and 50% of C and 50% of H. The contents were heated with stirring to a reaction temperature of 210xc2x0 C. until the mixture was clear and the acid value was  less than 10 mgKOH/g. At this point the remainder of C and H were charged and the temperature raised to 230xc2x0 C. The reaction was continued under reduced pressure until an acid value of 9.4 mg(KOH)gxe2x88x921 was obtained. The resin was further characterised by a hydroxyl value=12.8 mg(KOH)gxe2x88x921, ICI Cone and Plate Viscosity @125xc2x0 C.= greater than 500 poises and a Tg (onset)=18xc2x0 C. The number average molecular weight as determined by gel permeation chromatography (PS Equivalents) was 1800. The resin was readily dispersed in warm distilled water to give a clear solution having a solids content of 20% w/w (hereinafter xe2x80x9cResin 3xe2x80x9d).